Global stockpile

The planning involved in the switchover has included dealing with a global stockpile of 100 million doses of vaccine targeting just type 2, built up as an insurance policy in case of any outbreak.

The World Health Organization denied some media reports that "millions" of doses of the old vaccine would need to be destroyed, by incineration or other approved means.

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Mike Ray, who contracted polio when he was six, said he was "delighted" at the latest news

Its director of polio eradication, Michel Zaffran, said: "Some will need to be destroyed - but this will be a few vials, not trucks full of vaccine.

"This has been carefully planned because of the huge amount of resources, so countries have been using up the old vaccine, to minimise leftover quantities.

"We're closer than ever to ending polio worldwide, which is why we are able to move forward with the largest and fastest globally synchronised vaccine switchover."

Mike Ray, who contracted polio when he was six years old and has been affected for decades afterwards, told BBC Breakfast he was "absolutely delighted" at the latest news.

He said he was "exceedingly lucky" that he had never had calipers and has been able to get around using crutches and walking sticks.

"I'm not happy it's taken this long [to get close to eradicating the disease] because it has affected so many other people but more power to their elbow. [It is] great news."

Polio progress

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By 1988, polio had disappeared from the US, UK, Australia and much of Europe but remained prevalent in more than 125 countries. The same year, the World Health Assembly adopted a resolution to eradicate the disease completely by the year 2000.

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In 2015, polio remained endemic in only two countries - Pakistan and Afghanistan. There have been only 10 cases reported so far in 2016, all of which were in Pakistan and Afghanistan. Africa has been free of polio for more than a year.